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Gentoo Linux Security Advisory                           GLSA 201701-30
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                                           https://security.gentoo.org/
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 Severity: Normal
    Title: vzctl: Security bypass
     Date: January 11, 2017
     Bugs: #560522
       ID: 201701-30

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Synopsis
========

A vulnerability in vzctl might allow attackers to gain control over
ploop containers.

Background
==========

vzctl is a set of control tools for the OpenVZ server virtualization
solution.

Affected packages
=================

    -------------------------------------------------------------------
     Package              /     Vulnerable     /            Unaffected
    -------------------------------------------------------------------
  1  sys-cluster/vzctl            < 4.9.4                    >= 4.9.4

Description
===========

It was discovered that vzctl determined the virtual environment (VE)
layout based on the presence of root.hdd/DiskDescriptor.xml in the VE
private directory.  This allows local simfs container (CT) root users
to change the root password for arbitrary ploop containers.  This is
demonstrated by a symlink attack on the ploop container root.hdd file
which can then be used to access a control panel.

Impact
======

An attacker with root privileges, in a simfs-based container, could
gain control over ploop-based containers.

Workaround
==========

There is no known workaround at this time.

Resolution
==========

All vzctl users should upgrade to the latest version:

  # emerge --sync
  # emerge --ask --oneshot --verbose ">=sys-cluster/vzctl-4.9.4"

References
==========

[ 1 ] CVE-2015-6927
      http://nvd.nist.gov/nvd.cfm?cvename=CVE-2015-6927

Availability
============

This GLSA and any updates to it are available for viewing at
the Gentoo Security Website:

 https://security.gentoo.org/glsa/201701-30

Concerns?
=========

Security is a primary focus of Gentoo Linux and ensuring the
confidentiality and security of our users' machines is of utmost
importance to us. Any security concerns should be addressed to
security@gentoo.org or alternatively, you may file a bug at
https://bugs.gentoo.org.

License
=======

Copyright 2017 Gentoo Foundation, Inc; referenced text
belongs to its owner(s).

The contents of this document are licensed under the
Creative Commons - Attribution / Share Alike license.

http://creativecommons.org/licenses/by-sa/2.5